Will Dunham
April 29 (Reuters) – The fall of the Western Roman Empire in AD 476 was a pivotal moment in human history, when the German chieftain Odoacer deposed the teenage emperor of Italy, Romulus Augustus, and triggered the collapse of centralized power across much of Europe.
New research based on genomic data from residents of Roman-defended frontiers in what is now southern Germany documents how these dramatic political changes affected ordinary people while contradicting popular notions of “barbarian invasions” sweeping across the former territories of the defunct empire.
For example, the researchers found that abandoning imperial-era marriage restrictions led to rapid mixing of Roman garrisons and city populations with lower-status locals, including some of Norse ancestry.
“The temporal congruence between the decline of the Western Roman Empire in Italy and the genetic shift we detected in southern Germany is very precise,” said Joachim Burger, an anthropologist and population geneticist at the Johannes Gutenberg University in Mainz, Germany, and senior author of the study published Wednesday in the journal Nature.
The researchers analyzed the genomes of 258 people buried in so-called “row graves” in the modern German states of Bavaria and Hesse, including 112 people buried in the Bavarian village of Altheim. Most date to between 450 and 620 AD.
“Row cemeteries were an emerging early medieval burial method in which people were buried in rows, often containing grave goods such as clothing, jewelry and weapons. These cemeteries straddled the former Roman frontier, stretching from the Netherlands to Hungary,” said Jens Blöcher, a population geneticist at Johannes Gutenberg University Mainz and lead author of the study.
Roman authorities established military posts along the German borders to guard against invasions and disturbances, and some of these posts grew into larger settlements and eventually cities. These include Mainz, Regensburg, Trier and Cologne near the cemeteries participating in the study.
Genomic data reveal significant changes in population structure that coincided with the disintegration of Roman state structures at the end of the fifth century. It suggests that during the long twilight period of the Imperial Age, people from northern Europe, many of whom may have been agricultural workers, had migrated south into the region in small groups and lived separately from the wider Roman population. At the time, outsiders could acquire land on conditions such as marrying a Roman.
“They lived there for generations, marrying almost exclusively within their own group – preserving their northern genetic heritage,” Berg said.
Intermarriage and fusion
Research has found that Roman soldiers and civilians were genetically diverse, made up of ancestry from different parts of the empire. They are genetically distinct from the outsiders who slowly entered the region from northern Europe, including as far away as Britain, the Balkans and even Asia.
The genome reflects the intermarriage between the two groups after the empire’s fall and the peaceful mixing of peoples, culminating in the formation of a new early medieval society.
“While we do find movements of people from north to south across former imperial borders, most migrations occurred several generations before the critical horizon of the empire’s demise” and began in the third and fourth centuries, Berg said.
“Crucially, this influx was not driven by large, ethnically homogeneous tribal groups or major clans, but by small kin groups or even isolated individuals. This pattern directly contradicts the traditional narrative of a ‘massive barbarian invasion’ after the collapse of Rome,” Berg said.
Even before Romulus Augustus was overthrown, the vast Roman Empire had been divided into eastern and western parts. While the Western Roman Empire disintegrated after a long period of instability and military setbacks, the Eastern Roman Empire (later known as the Byzantine Empire), centered at Constantinople (modern-day Istanbul), continued to flourish.
The genomic data revealed the demographics of the people studied, with female life expectancy around 40 years and male life expectancy around 43 years, and infant mortality high in a society where nearly a quarter of children lose at least one parent by age 10.
Christianity had become the state religion of Rome. Genomic data indicate that the family is a monogamous core unit, with widows not remarrying within their husband’s family, and consanguineous marriages, such as first cousins, being strictly avoided.
“All of these features reflect Christian norms in late antiquity,” Berg said.
The data suggests that in the centuries after the empire’s fall, more northerners came to the region, and a new genetic profile emerged around the seventh century — “very similar to what we observe in central Europe today,” Berg said.
(Reporting by Will Dunham in Washington; Editing by Daniel Wallis)